A modern integrated circuit (IC), for example a flash memory device, may have millions to hundreds of millions of devices made up of complex, multi-layered structures that are fabricated through hundreds of processing steps. Those structures are formed by repeated deposition and patterning of thin films on a silicon substrate, also known as a wafer.
As device size shrinks, interfaces between operational components and periphery components also shrink. Although the shrinking of devices is important to the industry, a plurality of trouble spots begin to appear as portions of the device move closer together. For example, at the boundary between operational and non-operational devices, errors can occur due to the plurality of processes involved in manufacturing. For example, in a memory array there are a plurality of actual bitlines that are formed through layering, masking, and etching processes. At the edges of the memory array (e.g., the last couple of bitlines before the edge of the memory array), the masking processes may be less controllable due to changes in the topography of the underlying layers and/or pattern density. This is due to overspray, underspray, excess material application, lack of material application, or the like which may result in a loss of uniformity at the periphery.
To ensure quality of the memory device, most manufacturing processes incorporate an amount of space at the periphery or transitional points known as dummy space. Specifically, these are sections of manufacture that have high rates of error during the manufacturing process. Therefore, instead of trying to ensure each and every device is perfect and/or operationally sound, a manufacturer will just set a standard number (e.g., the last four or five) of lines of devices in a process that will be treated as throw away, non-operational (e.g., dummy) spaces. These spaces may have any or all of the manufacturing process performed thereon, however, they will be assumed to be flawed and treated as such.
Another solution to the loss of components on the edge of a memory array manufacturing process is to utilize the dummy space as a stand off for conformity and operational issues. For example, instead of cutting out the dummy space they may be used as a buffer zone against other manufacturing operations that will occur later in the process.
For example, during the manufacture of a flash memory device, a plurality of dummy bitlines may follow the plurality of actual bitlines. However, by maintaining a buffer zone of dummy bitline components, the memory device also retains an unnecessarily larger profile. Therefore, although they are necessary as buffers during the manufacturing process, they ultimately hinder the ability to further reduce a component's size. Additionally, if the dummy bitlines are decreased in size, it is apparent that further dummy bitlines must be necessarily incorporated to retain the desired distance between active bitlines and the interface between a memory array and interface circuitry (e.g., the interface of the manufacturing process).